Residues of 14-3-3 zeta required for activation of exoenzyme S of Pseudomonas aeruginosa

Biochemistry. 1999 Sep 14;38(37):12159-64. doi: 10.1021/bi991019l.


Exoenzyme S (ExoS) is a mono-ADP-ribosyltransferase secreted by the opportunistic pathogen Pseudomonas aeruginosa. ExoS requires a eukaryotic factor, the 14-3-3 protein, for enzymatic activity. Here, two aspects of the activation of the ADP-ribosyltransferase activity of ExoS by 14-3-3 proteins are examined. Initial studies showed that several isoforms of 14-3-3, including beta, zeta, eta, sigma, and tau, activated ExoS with similar efficiency. This implicates a conserved structure in 14-3-3 that contributes to the interaction between 14-3-3 and ExoS. One candidate structure is the conserved amphipathic groove that mediates the 14-3-3/Raf-1 interaction. The next series of experiments examined the role of individual amino acids of the amphipathic groove of 14-3-3 zeta in ExoS activation and showed that ExoS activation required the basic residues lining the amphipathic groove of 14-3-3 zeta without extensive involvement of the hydrophobic residues. Strikingly, mutations of Val-176 of 14-3-3 zeta that disrupted its interaction with Raf-1 did not affect the binding and activation of ExoS by 14-3-3. Thus, ExoS selectively employs residues in the Raf-binding groove for its association with 14-3-3 proteins.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 14-3-3 Proteins
  • ADP Ribose Transferases / metabolism*
  • Bacterial Toxins*
  • Binding Sites / genetics
  • Conserved Sequence
  • Enzyme Activation / genetics
  • Mutagenesis, Site-Directed
  • Poly(ADP-ribose) Polymerases / metabolism
  • Protein Isoforms / chemistry
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Isoforms / physiology
  • Proteins / chemistry
  • Proteins / genetics
  • Proteins / metabolism
  • Proteins / physiology*
  • Pseudomonas aeruginosa / enzymology*
  • Pseudomonas aeruginosa / genetics
  • Structure-Activity Relationship
  • Tyrosine 3-Monooxygenase*
  • Valine / genetics


  • 14-3-3 Proteins
  • Bacterial Toxins
  • Protein Isoforms
  • Proteins
  • Tyrosine 3-Monooxygenase
  • ADP Ribose Transferases
  • Poly(ADP-ribose) Polymerases
  • exoenzyme S
  • Valine